Fluid injection systems are used in numerous medical procedures that require injection of fluid into a patient. One non-limiting example of such a procedure is the treatment of coronary artery disease where an artery feeding into the heart has become obstructed or narrowed. In such conditions, an angioplasty, or stent placement, is often a prescribed treatment and in preparing for such procedures, an angiogram is performed.
In such procedures, a large volume of a radio-opaque “dye” or contrast media is injected into the vasculature of the patient to the site of obstruction. X-ray videos are then taken of the coronary arteries using the contrast media, thus providing an image of the location and severity of the blockage in the diseased vessel.
Due to the pressure and large volume of fluid being injected into a patient during cardiological procedure and many other types of procedures (e.g. MRI, CT, etc.), specialized injection systems have been developed which enclose and retain the injecting syringes during use. These systems typically use a disposable syringe since non-disposable syringes can oftentimes be impractical and prohibitive from a cost and process standpoint. Such systems restrict and prevent bursting or leakages of the pressurized fluid during use of the injecting syringe. Due to the safety and reliability requirements of systems containing such pressurized fluids, various pressure sleeve systems have been developed for medical use. Examples of these systems can be found in U.S. Pat. No. 5,899,885 and U.S. Pat. No. 5,779,675.
In each of the above-referenced patents, there is disclosed a fluid injection system that utilizes a specialized pressure sleeve designed to accommodate the biosafety requirements for each injection system. These pressure sleeve designs are also intended to simplify the operation of the injector by enabling the user to introduce the syringe into the injection system from the front of the system. Such designs are typically referred to as “front-loading” injection systems.
Although the front-loading systems disclosed in the above-referenced patents (and other similar devices not specifically described) offer improvements over the earlier pressure sleeve designs, such systems are not always optimal. For example, one disadvantage of a front-loading pressure sleeve design as shown is that a user can accidentally attempt to remove the syringe from the system when the syringe plunger is still engaged (at the rear end of the plunger) to the actuator ram of the injection system. If the syringe is successfully removed with the plunger still attached to the actuator, any remaining injection fluid will flood the pressure sleeve assembly and likely seep onto the actuator and eventually into the injector housing. Although not creating a biohazard, this undesirable result may somewhat reduce long term performance and thus, requires disassembly of the sleeve in order to thoroughly clean the system.
Another example of a disadvantage of the front-loading system such as discussed above is the difficulty in removing the syringe and/or pressure sleeve from the system if there has been any leakage or inadvertent spilling of injection media into the pressure sleeve. This difficulty results from the injection media solidifying or accumulating on the pressure sleeve surfaces and thereby inhibiting smooth movement of the syringe into or out of the pressure sleeve, as well as movement of the pressure sleeve out of the injector. Oftentimes, the only way to remove the syringe and/or pressure sleeve under such conditions is to pry the device out by hand or with some sort of makeshift tool.
In view of the above, it is apparent that although improvements in pressure vessel sleeves have been made, there is a continuing need to provide better pressure sleeve systems that are reliable and less likely to result in fluid contamination of the pressure sleeve assembly. There is also a need to provide an injection device having a pressure sleeve system that is simpler to use and easier to maintain. Such improved fluid injection systems include properties that reduce the amount of effort required prior to and during use of the system as well as properties that increase the device's range of applications.